Cardiac Power Output Revisited

Cardiogenic shock trajectories: is the Society for Cardiovascular Angiography and Interventions definition the right one?

PURPOSE OF REVIEW

We review the current Society for Cardiovascular Angiography and Interventions (SCAI) cardiogenic shock classification system and consider alternatives or iterations that may enhance our current descriptions of cardiogenic shock trajectory.

RECENT FINDINGS

Several studies have identified the potential prognostic value of serial SCAI stage re-assessment, usually within the first 24 h of shock onset, to predict deterioration and clinical outcomes across shock causes. In parallel, numerous registry-based analyses support the utility of a more precise assessment of the macrocirculation and microcirculation, leveraging invasive haemodynamics, imaging and additional laboratory and clinical markers. The emergence of machine learning and artificial intelligence capabilities offers the opportunity to integrate multimodal data into high fidelity, real-time metrics to more precisely define trajectory and inform our therapeutic decision making.

SUMMARY

Whilst the SCAI staging system remains a pivotal tool in cardiogenic shock assessment, communication and reassessment, it is vital that the sophistication with which we measure and assess shock trajectory evolves in parallel our understanding of the complexity and variability of clinical course and clinical outcomes.

Practical Guidance for Hemodynamic Assessment by Right Heart Catheterization in Management of Heart Failure

Heart failure is a clinical syndrome characterized by the inability of the heart to meet the circulatory demands of the body without requiring an increase in intracardiac pressures at rest or with exertion. Hemodynamic parameters can be measured via right heart catheterization, which has an integral role in the full spectrum of heart failure: from ambulatory patients to those in cardiogenic shock, as well as patients being considered for left ventricular device therapy and heart transplantation. Hemodynamic data are critical for prompt recognition of clinical deterioration, assessment of prognosis, and guidance of treatment decisions. This review is a field guide for hemodynamic assessment, troubleshooting, and interpretation for clinicians treating patients with heart failure.

Improved Prognostic Performance of Right Atrial Pressure-Corrected Cardiac Power Output in Pulmonary Hypertension and Heart Failure with Preserved Ejection Fraction

Cardiac power output (CPO) is a powerful predictor of adverse outcomes in heart failure (HF). However, the original formula of CPO included the difference between mean arterial pressure and right atrial pressure (RAP). The prognostic performance of RAP-corrected CPO (CPORAP) remains unknown in heart failure with preserved ejection fraction (HFpEF). We studied 101 HF patients with a left ventricular ejection fraction > 40% who had pulmonary hypertension due to left heart disease. CPORAP was significantly more discriminating than CPO in predicting outcomes (Delong test, P = 0.004). Twenty-five (24.8%) patients presented with dis-concordantly high CPORAP and low CPO when stratified by the identified CPORAP threshold of 0.547 W and the accepted CPO threshold of 0.803 W. These patients had the lowest RAP, and their cumulative incidence was comparable with those with concordantly high CPO and CPORAP (P = 0.313). CPORAP might identify patients with right ventricular involvement, thereby providing better prognostic performance than CPO in HFpEF.

Advanced hemodynamics for prognostication in heart failure: the pursuit of the patient-specific tipping point

Background

Objective tools to define the optimal time for referral for advanced therapies and to help guide escalation and de-escalation of support can improve management decisions and outcomes for patients with advanced heart failure. The current parameters have variable prognostic potential depending on the patient population being studied and often have arbitrary thresholds.

Methods

Here, a mathematical and physiological framework to define the patient-specific tipping point of myocardial energetics is defined. A novel hemodynamic parameter known as the myocardial performance score (MPS), a marker of power and efficiency, is introduced that allows for the objective assessment of the physiological tipping point. The performance of the MPS and other advanced hemodynamic parameters including aortic pulsatility index (API) and cardiac power output (CPO) in predicting myocardial energetics and the overall myocardial performance was evaluated using a validated computer simulation model of heart failure (Harvi) as well as a proof-of-concept clinical validation using a cohort of the Society for Cardiovascular Angiography and Interventions (SCAI) Stage C cardiogenic shock patients.

Results

Approximately 1010 discrete heart failure scenarios were modeled. API strongly correlated with the left ventricular coupling ratio (R2 = 0.81) and the strength of association became even stronger under loaded conditions where pulmonary capillary wedge pressure (PCWP) was >20 mmHg (R2 = 0.94). Under loaded conditions, there is a strong logarithmic relationship between MPS and mechanical efficiency (R2 = 0.93) with a precipitous rise in potential energy (PE) and drop in mechanical efficiency with an MPS <0.5. An MPS <0.5 was able to predict a CPO <0.6 W and coupling ratio of <0.7 with sensitivity (Sn) of 87%, specificity (Sp) of 91%, positive predictive value of 81%, and negative predictive value of 94%. In a cohort of 224 patients with SCAI Stage C shock requiring milrinone initiation, a baseline MPS score of <0.5 was associated with a 35% event rate of the composite endpoint of death, left ventricular assist device, or transplant at 30 days compared with 3% for those with an MPS >1 (p < 0.001). Patients who were able to augment their MPS to >1 after milrinone infusion had a lower event rate than those with insufficient reserve (40% vs. 16%, p = 0.01).

Conclusions

The MPS, which defines the patient-specific power-to-efficiency ratio and is inversely proportional to PE, represents an objective assessment of the myocardial energetic state of a patient and can be used to define the physiological tipping point for patients with advanced heart failure.

Right to Left Cardiac Power Output- New Prognosticator in STEMI Patients With Cardiogenic Shock (R-Shock)

ST elevation myocardial infarction (STEMI) is a leading cause of cardiogenic shock (CS) and carries substantial mortality. Cardiac power output (CPO) is the strongest predictor of clinical outcome in CS, and worse outcomes result from concomitant right and left ventricular failure. Right ventricular performance is calculated using right sided CPO. Our aim was to measure the right sided CPO and compute their ratio to predict in-hospital mortality in STEMI patients with cardiogenic shock. This was a retrospective observational study of consecutive STEMI patients with CS that developed within the first 24hours of admission requiring left and right cardiac catheterization at a large tertiary care center from January 2014-December 2018. One hundred sixty-four patients identified with STEMI; 46% (75) excluded due to incomplete data. 88 remaining patients, 52.8% (47) developed CS. 98.9% within 24 hours. Mean left & right CPO 0.62 (SD 0.3) and 0.22 (SD 0.13), PAPi score 1.81. Logistic regression analysis indicated odds ratio of in-hospital mortality lower for low left CPO, high right CPO and low ratio of left to right CPO (95% CI; 0.69, 0.34, 1.20; 1.38, 0.87, 2.20; 0.52, 0.28, 1.00 respectively). This is the first study to assess right sided CPO and ratio of right and left side CPO and mortality. Our study indicates that there is trend towards higher in-hospital mortality in patients with high right sided CPO and lower ratio of left to right CPO. The exploratory results of this study need to be confirmed in a larger population.

Impact of Cardiac Power Output on Exercise Capacity and Clinical Outcome in Patients With Chronic Heart Failure

Less data are available regarding the impact of cardiac power output on exercise capacity or clinical outcome in patients with chronic heart failure (CHF). The study enrolled 280 consecutive patients with CHF referred for cardiopulmonary exercise testing and right-sided heart catheterization between 2013 and 2018. The primary outcome was composite of heart failure hospitalization or death. Cardiac power output was calculated as (mean arterial pressure × CO) ÷ 451. Patients with low cardiac power output (<0.53 W, n = 99) were older and had a higher brain natriuretic peptide level than patients with high cardiac power output (≥0.53W, n = 181). Cardiac power output was correlated with peak oxygen consumption (peak V̇O2), peak workload achievement, and ventilatory efficiency (V̇E/V̇CO2 slope) in cardiopulmonary exercise testing, whereas each of cardiac output or mean arterial pressure was not. There were 48 patients with events over a median follow-up period of 3.5 (interquartile range 1.0 to 6.0) years. Patients with low cardiac power output had about a 2-fold higher risk of events than those with a high cardiac power output (hazard ratio 1.97, 95% confidence interval 1.12 to 3.48). In the multivariable Cox regression, a 0.1-W decrease in cardiac power output was associated with 19% increased adverse events (hazard ratio 0.81, 95% confidence interval 0.67 to 0.99). In conclusion, cardiac power output was associated with reduced exercise capacity and poor clinical outcome, suggesting that cardiac power output is useful for risk stratification in patients with CHF. Further study is required to identify therapies targeting cardiac power output to improve the exercise capacity or clinical outcome in patients with CHF.

State of Shock: Contemporary Vasopressor and Inotrope Use in Cardiogenic Shock

Cardiogenic shock is characterized by tissue hypoxia caused by circulatory failure arising from inadequate cardiac output. In addition to treating the pathologic process causing impaired cardiac function, prompt hemodynamic support is essential to reduce the risk of developing multiorgan dysfunction and to preserve cellular metabolism. Pharmacologic therapy with the use of vasopressors and inotropes is a key component of this treatment strategy, improving perfusion by increasing cardiac output, altering systemic vascular resistance, or both, while allowing time and hemodynamic stability to treat the underlying disease process implicated in the development of cardiogenic shock. Despite the use of mechanical circulatory support recently garnering significant interest, pharmacologic hemodynamic support remains a cornerstone of cardiogenic shock management, with over 90% of patients receiving at least 1 vasoactive agent. This review aims to describe the pharmacology and hemodynamic effects of current pharmacotherapies and provide a practical approach to their use, while highlighting important future research directions.

Biventricular cardiac power reserve in heart failure with preserved ejection fraction

AIMS

Cardiac and extracardiac abnormalities play important roles in heart failure with preserved ejection fraction (HFpEF). Biventricular cardiac power output (BCPO) quantifies the total rate of hydraulic work performed by both ventricles, suggesting that it may help to identify patients with HFpEF and more severe cardiac impairments to better individualize treatment.

METHODS AND RESULTS

Patients with HFpEF (n = 398) underwent comprehensive echocardiography and invasive cardiopulmonary exercise testing. Patients were categorized as low BCPO reserve (n = 199, < median of 1.57 W) or preserved BCPO reserve (n = 199). As compared to those with preserved BCPO reserve, those with low reserve were older and leaner, with more atrial fibrillation, higher N-terminal pro-B-type natriuretic peptide levels, worse renal function, more impaired left ventricular (LV) global longitudinal strain, worse LV diastolic function and right ventricular longitudinal function. Cardiac filling pressures and pulmonary artery pressures at rest were higher in low BCPO reserve, but central pressures were similar during exercise to those with preserved BCPO reserve. Exertional systemic and pulmonary vascular resistances were higher and exercise capacity was more impaired in those with low BCPO reserve. Reduced BCPO reserve was associated with increased risk for the composite endpoint of heart failure hospitalization or death over 2.9 (interquartile range 0.9-4.5) years of follow-up (hazard ratio 2.77, 95% confidence interval 1.73-4.42, p < 0.0001).

CONCLUSIONS

Inability to enhance BCPO during exercise is associated with more advanced HFpEF, increased systemic and pulmonary vascular resistance, reduced exercise capacity and increased adverse events in patients with HFpEF. Novel therapies that enhance biventricular reserve merit further investigation for patients with this phenotype.

Associations of right ventricular pulsatile load and cardiac power output to clinical outcomes in heart failure: Difference from systemic circulation

BACKGROUND

Although left ventricular (LV) cardiac power output (CPO) is a powerful prognostic indicator in heart failure (HF), the significance of right ventricular (RV) CPO is unknown. In contrast, RV pulsatile load is a key prognostic marker in HF. We investigated the impact of RV-CPO and pulsatile load on cardiac outcome and the prognostic performance of the combined systemic and pulmonary circulation parameters in HF.

METHODS

Right heart catheterization and echocardiography were performed in 231 HF patients (62 ± 16 years, LV ejection fraction 42 ± 18 %). Invasive and noninvasive CPOs were calculated from mean systemic or pulmonary arterial pressure and cardiac output. LV-CPO was then normalized to LV mass (LV-P/M). Pulmonary arterial capacitance and the ratio of acceleration time to ejection time (AcT/ET) of RV outflow were used as parameters of RV pulsatile load. The primary endpoints, defined as a composite of cardiac death, HF hospitalization, ventricular arrythmia, and LVAD implantation after the examination, were recorded.

RESULTS

Noninvasive CPOs were moderately correlated with invasive ones (LV: ρ = 0.787, RV: ρ = 0.568, and p < 0.001 for both). During a median follow-up period of 441 days, 57 cardiovascular events occurred. Lower LV-P/M and higher RV pulsatile load were associated with cardiovascular events; however, RV-CPO was not associated with the outcome. Echocardiographic LV-P/M and AcT/ET showed significant incremental prognostic value over the clinical parameters.

CONCLUSIONS

RV pulsatile load assessed by AcT/ET may be a predictor of clinical events in HF patients. The combination of echocardiographic LV-P/M and AcT/ET could be a novel noninvasive prognostic indicator in HF patients.

Review of Pathophysiology of Cardiogenic Shock and Escalation of Mechanical Circulatory Support Devices

PURPOSE OF REVIEW

Cardiogenic shock (CS) is a complex clinical entity that continues to carry a high risk of mortality. The landscape of CS management has changed with the advent of several temporary mechanical circulatory support (MCS) devices designed to provide hemodynamic support. It remains challenging to understand the role of different temporary MCS devices in patients with CS, as many of these patients are critically ill, requiring complex care with multiple MCS device options. Each temporary MCS device can provide different types and levels of hemodynamic support. It is important to understand the risk/benefit profile of each one of them for appropriate device selection in patients with CS.

RECENT FINDINGS

MCS may be beneficial in CS patients through augmentation of cardiac output with subsequent improvement of systemic perfusion. Selecting the optimal MCS device depends on several variables including the underlying etiology of CS, clinical strategy of MCS use (bridge to recovery, bridge to transplant or durable MCS, or abridge to decision), amount of hemodynamic support needed, associated respiratory failure, and institutional preference. Furthermore, it is even more challenging to determine the appropriate time to escalate from one MCS device to another or combine different MCS devices. In this review, we discuss the current available data published in the literature on the management of CS and propose a standardized approach for escalation of MCS devices in patients with CS. Shock teams can play an important role to help in hemodynamic-guided management and algorithm-based step-by-step approach in early initiation and escalation of temporary MCS devices at different stages of CS. It is important to define the etiology of CS, and stage of shock and recognize univentricular vs biventricular shock for appropriate device selection and escalation of therapy.

Phenotyping and Hemodynamic Assessment in Cardiogenic Shock: From Physiology to Clinical Application

There is growing interest in invasive hemodynamic assessment in cardiogenic shock, primarily due to the widespread adoption of mechanical circulatory support (MCS). Invasive hemodynamic assessment is central to two aspects of cardiogenic shock management: (1) the phenotyping of cardiogenic shock, and (2) the assessment of response to therapy. Phenotyping of cardiogenic shock serves to guide timely therapeutic intervention, and the assessment of hemodynamic response to therapy directs the escalation or de-escalation of therapy, including MCS. This review aims to discuss these two aspects of hemodynamic assessment in cardiogenic shock. Firstly, the physiologic underpinnings of a phenotyping schema, and the implication of the cardiogenic shock phenotype on the MCS strategy in cardiogenic shock will be discussed. Secondly, the concept of cardiac power output and 'effective' oxygen delivery will be discussed in relation to hemodynamic response to therapy in cardiogenic shock.

Prognostic Role of Cardiac Power in a Large Cohort of Patients with Normal Ejection Fraction Referred for Dobutamine Stress Echocardiography

BACKGROUND

Cardiac power reflects cardiac performance in terms of energy transferred by the left ventricle (LV) to the aorta per unit time. Peak stress cardiac power has been shown to predict outcome in patients with reduced LV ejection fraction (EF), and more recently, in patients with normal EF referred for exercise stress echocardiography. We sought to evaluate the prognostic significance of cardiac power in patients with normal EF referred for dobutamine stress test (DSE).

METHODS

We studied data from 15,576 patients with EF ≥50% and no significant valvular or right ventricular dysfunction, undergoing DSE. Cardiac power at rest and peak stress and power reserve (peak stress minus rest power) were calculated and normalized to LV mass. Outcome endpoints were all-cause mortality and new-onset heart failure (HF).

RESULTS

The mean age was 66±13 years and 49% patients were females. Resting and peak stress power/mass were 0.7±0.2 and 1.6±0.6 W/100 g of LV myocardium, respectively. During follow-up [median 3.3 (IQR 0.7-7.3) years], 2,278 patients died and 2,137 developed HF. After adjusting for age, sex, comorbidities, and stress test results, lower peak stress power/mass was independently associated with mortality [adjusted hazard ratio (HR), highest vs. lowest quartile, 0.84, 95% confidence intervals (CI) 0.74-0.95, P=0.004] and HF at follow-up [adjusted HR 0.67, 95% CI 0.59-0.76, P<0.0001]. Power reserve showed similar associations with outcomes.

CONCLUSION

Assessment of cardiac power during DSE in patients with normal EF provides valuable prognostic information regarding risk of mortality and future HF, in addition to stress test results. It is an important research tool to study cardiac performance and development of risk scores incorporating this novel index could be considered after further validation in prospective studies.

Cardiac power output index to define hemodynamic response to Impella support in cardiogenic shock

BACKGROUND

Early assessment of response to Impella in cardiogenic shock may guide escalation of mechanical circulatory support. Therapeutic goal and response to Impella have not previously been defined. This study tested the hypothesis that targeting 3-h post- Impella cardiac power output index (CPOi)-"hemodynamic response"-in cardiogenic shock is associated with 12-h lactate clearance.

METHODS

Single-center study of 37 consecutive patients who underwent left-sided Impella support for cardiogenic shock due to either acute myocardial infarction or decompensated heart failure. Patients who achieved 3-h post-Impella CPOi ⩾ 0.30 W/m² were defined as Impella "hemodynamic responder."

RESULTS

Twelve of the thirty-seven patients achieved 3-h post-impella CPOi  ⩾ 0.30 W/m² ("hemodynamic responders"). Post-Impella CPOi correlated with 12-h lactate (r = -0.779, p < 0.001) and lactate clearance (r = 0.747, p < 0.001). "Hemodynamic responders" had lower 12-h lactate level and greater 12-h lactate clearance (52 (44-58) vs 17 (14-26)%, p < 0.001). Higher pre-Impella norepinephrine dose (-0.341, p = 0.003) and baseline lactate (-0.009, p = 0.003) were independently associated with lower 3-h post-Impella CPOi. Eighteen patients died within 30 days (2/12 "hemodynamic responders" compared to 16/25 "non-responders," p < 0.001).

CONCLUSION

Patients who achieved early 3-h post-Impella CPOi of ⩾0.30 W/m² have greater lactate clearance and better short-term survival. Early post-Impella CPOi of 0.30 W/m² may be used as a therapeutic goal and define favorable response to Impella in cardiogenic shock.

A Comprehensive Review of Mechanical Circulatory Support Devices

Treatment strategies to combat cardiogenic shock (CS) have remained stagnant over the past decade. Mortality rates among patients who suffer CS after acute myocardial infarction (AMI) remain high at 50%. Mechanical circulatory support (MCS) devices have evolved as novel treatment strategies to restore systemic perfusion to allow cardiac recovery in the short term, or as durable support devices in refractory heart failure in the long term. Haemodynamic parameters derived from right heart catheterization assist in the selection of an appropriate MCS device and escalation of mechanical support where needed. Evidence favouring the use of one MCS device over another is scant. An intra-aortic balloon pump is the most commonly used short-term MCS device, despite providing only modest haemodynamic support. Impella CP® has been increasingly used for CS in recent times and remains an important focus of research for patients with AMI-CS. Among durable devices, Heartmate® 3 is the most widely used in the USA. Adequately powered randomized controlled trials are needed to compare these MCS devices and to guide the operator for their use in CS. This article provides a brief overview of the types of currently available MCS devices and the indications for their use.

Noninvasive echocardiographic cardiac power output predicts mortality in cardiac intensive care unit patients

BACKGROUND

Low cardiac power output (CPO), measured invasively, can identify critically ill patients at increased risk of adverse outcomes, including mortality. We sought to determine whether non-invasive, echocardiographic CPO measurement was associated with mortality in cardiac intensive care unit (CICU) patients.

METHODS

Patients admitted to CICU between 2007 and 2018 with echocardiography performed within one day (before or after) admission and who had available data necessary for calculation of CPO were evaluated. Multivariable logistic regression determined the relationship between CPO and adjusted hospital mortality.

RESULTS

A total of 5,585 patients (age of 68.3 ± 14.8 years, 36.7% female) were evaluated with admission diagnoses including acute coronary syndrome (ACS) in 56.7%, heart failure (HF) in 50.1%, cardiac arrest (CA) in 12.2%, shock in 15.5%, and cardiogenic shock (CS) in 12.8%. The mean left ventricular ejection fraction (LVEF) was 47.3 ± 16.2%, and the mean CPO was 1.04 ± 0.37 W. There were 419 in-hospital deaths (7.5%). CPO was inversely associated with the risk of hospital mortality, an association that was consistent among patients with ACS, HF, and CS. On multivariable analysis, higher CPO was associated with reduced hospital mortality (OR 0.960 per 0.1 W, 95CI 0.0.926-0.996, P = .03). Hospital mortality was particularly high in patients with low CPO coupled with reduced LVEF, increased vasopressor requirements, or higher admission lactate.

CONCLUSIONS

Echocardiographic CPO was inversely associated with hospital mortality in unselected CICU patients, particularly among patients with increased lactate and vasopressor requirements. Routine calculation and reporting of CPO should be considered for echocardiograms performed in CICU patients.

Cardiac Power Output Is Independently and Incrementally Associated With Adverse Outcomes in Heart Failure With Preserved Ejection Fraction

BACKGROUND

Cardiac power output is a measure of cardiac performance, and its prognostic significance has been shown in heart failure (HF) with reduced ejection fraction. Patients with HF with preserved ejection fraction may have altered cardiac performance, but the prognostic relevance of cardiac power output is unknown. This study sought to determine the association between cardiac power output and clinical outcomes in HF with preserved ejection fraction and to compare its prognostic effect to other measures of cardiac performance including ventricular-arterial coupling and mechanical efficiency.

METHODS

Cardiac power output normalized to left ventricular mass was assessed by echocardiography in 408 patients with HF with preserved ejection fraction. Load-independent contractility (end-systolic elastance), arterial elastance, its coupling (arterial elastance/end-systolic elastance), left ventricular global longitudinal strain, and mechanical efficiency (stroke work/pressure-volume area) were also estimated noninvasively. The primary end point was a composite of cardiovascular mortality or HF hospitalization.

RESULTS

The primary composite outcome occurred in 84 patients during a median follow-up of 19.4 months. There was a dose-dependent association between cardiac power output and the composite outcomes, in which patients with the lowest tertile of cardiac power output had >3-fold risk than those with the highest tertile (hazard ratio, 3.04 [95% CI, 1.66-5.57]; P=0.0003). In a multivariable model, lower cardiac power output was independently associated with adverse outcomes (hazard ratio, 0.70 per 1 SD [95% CI, 0.49-0.97]; P=0.03). In contrast, left ventricular size, end-systolic elastance, arterial elastance, arterial elastance/end-systolic elastance ratio, and left ventricular mechanical efficiency were not associated with outcomes. Cardiac power output provided an incremental prognostic effect over the model based on clinical (age, gender, diastolic blood pressure, and atrial fibrillation) and echocardiographic markers (left atrial size, pulmonary pressures, global longitudinal strain, and the ratio of early diastolic mitral inflow velocity to early diastolic mitral annular tissue velocity; P=0.03).

CONCLUSIONS

In patients with HF with preserved ejection fraction, cardiac power output was independently and incrementally associated with adverse outcomes whereas other markers of cardiac performance were not.

Overcoming the Limits of Ejection Fraction and Ventricular-Arterial Coupling in Heart Failure

Left ventricular ejection fraction (LVEF) and ventricular-arterial coupling (VAC) [VAC = Ea/Ees; Ea: effective arterial elastance; Ees: left ventricle (LV) elastance] are both dimensionless ratios with important limitations, especially in heart failure setting. The LVEF to VAC relationship is a divergent non-linear function, having a point of intersection at the specific value of 0.62, where V0 = 0 ml (V0: the theoretical extrapolated value of the volume-axis intercept at end-systolic pressure 0 mmHg). For the dilated LV, both LVEF and VAC are highly dependent on V0 which is inconclusive when derived from single-beat Ees formulas. VAC simplification should be avoided. Revisiting the relationship between systolic time intervals (STI), pressure, and volumes could provide simple-to-use guiding formulas, affordable for daily clinical practice. We have analyzed by echocardiography the hemodynamics of 21 patients with severe symptomatic heart failure with reduced ejection (HFrEF) compared to 12 asymptomatic patients (at risk of heart failure with mild structural disease). The groups were unequivocally separated by ‘classic’ measures (LVEF, LV end-systolic volume (ESV), LV mass, STI). Chen's Ees formula was weakly correlated with LVEF and indexed ESV (ESVi) but better correlated to the pre-ejection period (PEP); PEP/total ejection time (PEP/TET); systolic blood pressure/PEP (SBP/PEP) (P < 0.001). Combining the predictability of the LVEF to the determinant role of SBP/PEP on the Ees variations, we obtained: (SBP^*LVEF)/PEP mm Hg/ms, with an improved R² value (R² = 0.848; P < 0.001). The strongest correlations to VAC were for LVEF (R = −0.849; R² = 0.722) and PEP/TET (R = 0.925; R² = 0.857). By multiple regression, the VAC was strongly predicted (N = 33): (R = 0.975; R² = 0.95): VAC = 0.553–0.009^*LVEF + 3.463^*PEP/TET, and natural logarithm: Ln (VAC) = 0.147–1.4563^*DBP/SBP^*0.9–0.010^*LVEF + 4.207^*PEP/TET (R = 0.987; R² = 0.975; P = 0) demonstrating its exclusive determinants: LVEF, PEP/TET, and DBP/SBP. Considering Ea as a known value, the VAC-derived Ees formula: Ees_d ≈ Ea/(0.553–0.009^*LVEF+3.463^*PEP/TET) was strongly correlated to Chen's Ees formula (R = 0.973; R² = 0.947) being based on SBP, ESV, LVEF, and PEP/TET and no exponential power. Thus, the new index supports our hypothesis, in the limited sample of patients with HFrEF. Indices like SBP/PEP, (SBP^*LVEF)/PEP, PEP/TET, and DBP/SBP deserve further experiments, underlining the major role of the forgotten STI.

Hemodynamics for the Heart Failure Clinician: A State-of-the-Art Review

Heart failure (HF) fundamentally reflects an inability of the heart to provide adequate blood flow to the body without incurring the cost of increased cardiac filling pressures. This failure occurs first during the stressed state, but progresses until hemodynamic derangements become apparent at rest. As such, the measurement and interpretation of both resting and stressed hemodynamics serve an integral role in the practice of the HF clinician. In this review, we discuss conceptual and technical best practices in the performance and interpretation of both resting and invasive exercise hemodynamic catheterization, relate important pathophysiologic concepts to clinical care, and discuss updated, evidence-based applications of hemodynamics as they pertain to the full spectrum of HF conditions.

Improved Prognostic Performance of Cardiac Power Output With Right Atrial Pressure: A Subanalysis of the ESCAPE Trial

BACKGROUND

The initial derivation of cardiac power output (CPO) included the difference between mean arterial pressure (MAP) and right atrial pressure (RAP) in the numerator, before multiplying by cardiac output (CO). We hypothesized that the inclusion of RAP (CPO-RAP) would enhance the prognostic performance of this parameter in those with an elevated RAP.

METHODS AND RESULTS

We obtained patient-level data from the ESCAPE trial via the Biolincc database. Participants with full final hemodynamics were included in the analysis. The CPO-RAP was calculated as [(MAP - RAP) × CO)]/451 Watts (W), and the CPO was calculated as (MAP × CO)/451. The primary outcome was freedom from left ventricular assist device, heart transplant, or death at 6 months. Included participants (n = 157) were a median of 58 years of age (interquartile range [IQR] 49-67 years), 27% were women, and 59% had ischemic cardiomyopathy. The median CPO was 0.70 W (IQR 0.50-0.90 W), and the median CPO-RAP was 0.62 W (IQR 0.47-0.79 W). In univariable logistic regressions, the CPO was not associated with the primary outcome (odds ratio 0.32, 95% confidence interval 0.08-1.29, P = .11), but the CPO-RAP was (odds ratio 0.10, 95% confidence interval 0.02-0.54, P < .01). In Kaplan-Meier analyses, there were no significant difference in outcomes with CPO (76% vs 64%, P = .08), but for CPO-RAP, there were significant differences in outcomes (81% vs 63%, P = .01). When further delineating CPO-RAP by RAP above or below the median, there was no significant difference in the outcome for participants with a RAP 8 or less (94% vs 79%, P = .07), but a significant difference in participants with a RAP of more than 8 mm Hg (66% vs 45%, P < .05).

CONCLUSIONS

The inclusion of RAP resulted in a significant association with the primary outcome; CPO alone was not.

The contemporary pulmonary artery catheter. Part 2: measurements, limitations, and clinical applications

Nowadays, the classical pulmonary artery catheter (PAC) has an almost 50-year-old history of its clinical use for hemodynamic monitoring. In recent years, the PAC evolved from a device that enabled intermittent cardiac output measurements in combination with static pressures to a monitoring tool that provides continuous data on cardiac output, oxygen supply and-demand balance, as well as right ventricular performance. In this review, which consists of two parts, we will introduce the difference between intermittent pulmonary artery thermodilution using bolus injections, and the contemporary PAC enabling continuous measurements by using a thermal filament which heats up the blood. In this second part, we will discuss in detail the measurements of the contemporary PAC, including continuous cardiac output measurement, right ventricular ejection fraction, end-diastolic volume index, and mixed venous oxygen saturation. Limitations of all of these measurements are highlighted as well. We conclude that thorough understanding of measurements obtained from the PAC is the first step in successful application of the PAC in daily clinical practice.